The present invention relates to a needle selecting arrangement for knitting machines. More particularly, it relates to a needle selecting arrangement for such knitting machines which are provided with electromagnetic selecting elements, pressure strips and cam parts associated with the knitting systems and assembled in blocks, for selective actuation of needles, and also with a plurality of plates which are displaceable in the direction of elongation of the needles and act upon the needles. They are used especially in flat knitting machines with a reciprocating or single acting knitting systems, and can also be modified to be used for round knitting machines.
Needle selecting arrangements of this type are known in the art. In known needle selecting arrangements the electromagnetic selecting elements act via rockers on plates which are formed with a needle pusher and which act on the needles. The plates are pressed by a switchable pusher cam in different tracks and enable the selection of needles in fully extended, catching and not knitting positions. The disadvantage of this construction is, however, that significant space is required for actuation of the rockers and for the pusher cam, whereby the needle beds must be provided with very long passages and also with very large knitting carriages.
The DE-OS No. 2,842,054 discloses a needle selecting arrangement in which the needles during the knitting can be selected by needle plates which move in a longitudinal direction of the needles and are pressable in a springy manner in a needle bed, a pre-pressing member which acts upon the needle plates is engageable in several tracks, and selection plates are located above the same and actuatable by adjusting members associated with the knitting carriage, for forming stitches, catch hooks or floating threads. The adjusting members are arranged in a stepped manner in the knitting carriage and each adjusting member is located against the foot of a selecting plate. The insertion of the pre-pressing member into the desired track as well as displacement of it to its basic position is performed by special cam parts additionally arranged in the knitting carriage. This solution is very expensive because of many cooperating members from the selecting plate to the needle, which are arranged in the needle bed partially behind one another and over one another and act individually, and whose position must be secured. The cam has a complicated construction and a very long needle bed is required. Even smallest tolerance deviations between the needle bed and the knitting carriage can lead to false switches.
Finally, the DE-OS No. 2,939,639 also describes a selecting arrangement in which a plate located in each needle passage is actuated by electromagnet adjusting member and simultaneously serves for direct needle control. For differentiating the needles which make the stitches and the hooks or retaining them in non-operative condition, a two-step selection is required in the knitting cam and thereby two selecting blocks are needed for each knitting system. This means that high expenses are involved in the control electronic circuitry for this selecting system.
All above described solutions have the same disadvantage that the plate bed must be maintained clean, with great difficulties, for avoiding impurities of the adjusting members which move over the plate bed, since otherwise the impurities would affect their operational accuracy.